Two analyst firms released market numbers for the third quarter of 2007, and by both accounts, the WAN optimization market (compare products) is going strong.

Worldwide sales of WAN optimization appliances grew 20% in the third quarter of 2007, as compared to second-quarter figures, and unit shipments grew 16%, says research and consulting firm Infonetics Research, which just released its latest quarterly report on enterprise routers and WAN optimization appliances.

Among WAN optimization vendors, Riverbed Technology held the lead in market share, followed by Cisco and Bluecoat Systems, the firm reports.

In the big picture, quarterly manufacturer revenue for WAN optimization appliances has almost doubled over the past year, from the third quarter of 2006 to the third quarter of 2007, Infonetics’ report shows.

There are no signs that growth will halt, either.

“The WAN optimization market continues to do well; we expect another sequential gain in the fourth quarter, ending the year on an up note, and 65% year-over-year annual growth,” said Infonetics Research directing analyst Matthias Machowinski.

Looking ahead even further, Infonetics Research is forecasting that unit shipments of WAN optimization appliances will quadruple between 2006 and 2010.

Gartner analysts Joe Skorupa and Nhat Pham painted an equally healthy picture of the application acceleration market in their research firm’s third-quarter 2007 statistics

The worldwide application acceleration equipment market continued to grow in the third quarter, with revenue up by 13% to $554 million, Gartner reports.

Gartner divides the market into two segments: Application delivery controllers, which typically reside in the data center and focus on improving performance of Web and IP-based applications; and WAN optimization controllers, which reside in data centers and remote locations and focus on performance problems caused by WAN issues such as bandwidth and latency.

Application delivery controller revenue grew by 7%, to $307 million in the third quarter of 2007, while WAN optimization controller revenue rose by 22%, to $247 million, Gartner reports.

Ann Bednarz is associate news editor at Network World.